The 2000 series Cubs would go close the being one of the best all round mowers ever built, tough as nails and almost indestructible.
Bad news is MTD has discontinued support for them so 2000 serices specific parts will only get harder to find.
I started a war last time I mentioned that deck spindles are NLA from the warehouse so as the shops run out of stock that is it.
It is possible to modify currect MTD decks to fit, but they are only about 20% as strong as the original deck.
You ill find most of the information about your mower and the transmission on this site
"K&T Parts House Lawn Mower Parts and Chain Saw & Trimmer Parts" just find your models on the relevant pages & download them.
Posting your mowers serial number and also the thpe and model nuber of the transmission will help the people on this list help you better.
The only part I had had difficulty finding were bonnet panels and deck spindles and I have around 20 2000 series Cubs on my books now as I keep buying up old ones and reselling them.
They are fantastic mowers and well worth the effort of repairing .
Once fixed properly they wil give you at least twice the service life of any new mower out of the AYP factory as they were built as a light compact tractor designed to run rotary hoes, disc ploughs, snow blades & throwers, not just a mowing deck.